It varies, Usually I build a few layers and then pop the piece into my 'oven' (Which is basically a closed box with a couple of 100watt bulbs mounted in the bottom) overnight to harden. As for sculpting, This is all done using bits of tissue saturated with pva. which I then layer over with strips latticework style. If anyone is genuinely interested in my technique, (Now that I know how ) I could do a series of photos to illustrate it.